Variable stroke swash plate mechanism and adjusting means therefor



y 1970 R. H. BRANDES VARIABLE STROKE SWASH PLATE MECHANISM AND ADJUSTING MEANS THEREFOR Filed July 9, 1968 INVENTOR. (90 H 6?:wdes BY ATTORNEY 3 511,102 VARIABLE STROKE SWASH PLATE MECHANISM AND ADJUSTING MEANS THEREFOR Roy H. Brandes, Utica, Mich., assiguor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed July 9, 1968, Ser. No. 743,480 Int. Cl. F16b 33/ 1 F02b 75/04; F01b 13/04 U.S. Cl. 74--60 3 Claims ABSTRACT OF THE DISCLOSURE In a preferred embodiment, a hot gas engine includes a swash plate mechanism which is adjustable for varying the stroke of the engine pistons. Adjustment of the swash plate is accomplished by an adjusting screw actuated by gear means which are engaged by one of two hydraulic clutches to rotate the adjusting screw in a stroke lengthening or stroke shortening direction, as desired.

FIELD OF THE INVENTION This invention relates to adjustable swash plate mechanisms especially for use as a variable stroke drive for a reciprocating piston machine. In its more particular aspects, the invention relates to the combination of such mechanisms in a hot gas engine of the Stirling cycle type so as to provide means for controlling the speed and power of the engine by varying the stroke lengths of the pistons.

DESCRIPTION OF THE PRIOR ART The use of swash plate mechanisms, sometimes called wobble plate mechanisms, is Well known in the art relating to reciprocating piston machines including engines, pumps and the like. It is also known to vary the angular position of such a swash plate in order to vary the stroke of the pistons and thus change the operating characteristics of the machine. It is further known in the prior art to construct a hot gas engine having a plurality of cylinders reciprocating on parallel axes and delivering power to a crankshaft through a fixed angle wobble plate mechanism. One such arrangement is disclosed in FIGS. 4 and 5 of US. Pat. No. 2,480,525Van Weenen.

SUMMARY OF THE INVENTION The present invention relates to variable angle (adjustable) swash plate mechanisms for use in reciprocating piston machines. A particular arrangement encompassed by the invention provides rotatable adjusting means which are actuated through the engagement of clutch means so as to use the rotation of the swash plate in its housing as a source of power for adjusting the plate angle. Although the proposed arrangement is particularly intended for use in a hot gas engine of the Stirling cycle type, its use is not so limited and might be appropriately extended to other reciprocating piston machines.

When used in a Stirling engine, the arrangement has the advantage that hydraulic or other fluid pressure controlled by a governor or throttle may be used to actuate the clutches so as to increase or decrease the swash plate angle. This, in turn, controls the piston stroke which determines the power output of the engine and thus a. simple means of controlling engine speed of power is provided. Other objects and advantages of the invention will be apparent from the following description of a preferred embodiment taken in conjunction with the drawing.

United States Patent 0 BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is a cross-sectional view, schematically representing a Stirling cycle hot gas engine having an adjustable swash plate variable stroke mechanism according to the invention;

FIG. 2 is a cross-sectional view taken in the plane generally indicated by the line 2--2 of FIG. 1 and showing one of the gear adjusting means; and

FIG. 3 is a cross-sectional view taken in the plane generally indicated by the line 3-3 of FIG. 1 and illustrating the other gear adjusting means.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing, numeral 10 generally indicates a hot gas engine of the Stirling cycle type having a housing 12 in which are reciprocably disposed a plurality of pistons (not shown) connected to a reciprocable shaft 14. Although only one shaft 14 is illustrated, it should be understood that numerous such shafts could be spaced on parallel axes around the periphery of the engine housing and that reciprocating pistons could be disposed on either or both ends of such shafts.

Housing 12 also supports on bearings 16 a rotor 18 on which is pivotally supported a swash plate or wobble plate 20. Swash plate 20 is arranged to pivot on a laterally extending shaft 22 and has a circular periphery 24 having an outwardly opening groove 26 extending therearound. A pair of slide bearings 28 are received within groove 26 and connect therein with a spherical ball 30 which is secured to shaft 14 for reciprocation therewith.

In the swash plate inwardly of groove 26, a recessed portion 32 receives the spherical end 34 of a traveling nut 36. Nut 36 is carried for longitudinal movement on the threaded portion 38 of a positioning or adjusting screw 40 which is rotatably supported in bearings 42 mounted in the rotor 18. At one end, adjusting screw 40 has a gear wheel 44 which is engaged with a first adjusting gear 46 carried for rotation on the rotor by bearings 48. The gear 46 is arranged to be engaged by the friction surface 50 of reciprocable clutch piston 52 for a purpose to be subsequently described. Piston 52 includes a suitable seal such as O ring 54 to prevent leakage of fluid from a chamber 56 behind the piston which connects through conduit 58 with a source of pressure fluid such as a governor or throttle device.

At the end opposite gear 44, adjusting screw 40 has a second gear wheel 60. Gear wheel 60 engages an idler gear 62 which, in turn, engages a second adjusting gear 64. Gears 62 and 64 are rotatably mounted on the housing on bearings 66 and 68 respectively. Adjusting gear '64 is adapted to be engaged by the friction surface 70 of a second reciprocable clutch piston 72 which, like piston 52, includes seal means 74 and is open to a fluid chamber 76 that connects through a conduit 78 with a source of fluid pressure.

The operation of the construction is as follows. Reciprocating action of the shaft 14 in response to gas forces applied to the engine pistons causes the swash plate 20 to be rotated in a desired direction, depending on the construction and operation of the engine. The housing 12, with its reciprocating shaft 14, of course, remains stationary.

If it is desired to change the stroke of the pistons so as to alter the speed or power of the engine, a hydraulic or other fluid pressure is applied to the appropriate one of the pistons 52, 72. Assuming the pressure is applied to piston 52, friction surface 50 contacts adjusting gear 46, the rotation of which is thus slowed down or stopped.

This causes rotation of the gear train and adjusting screw 40 in the rotor, traversing the nut 36 and changing the angular position of the swash plate 20 accordingly. The change in position reduces or increases the power of the engine as the stroke of the pistons is reduced or increased by the previously described action which, of course, depens on the original position of the swash plate, direction of lead on the adjusting screw and the direction of rotation of the rotor.

If then, it is desired to make a change in power in the engine, opposite to that made by the previously described method, it is only necessary to apply fluid pres sure through conduit 78 to actuate piston 72 with its friction surface 70 into engagement with its adjusting gear 64. Through the engagement of gear 64 with idler gear 62 and gear wheel 60, this action rotates the adjusting screw 40 in the opposite direction to the previously described action, returning the nut 36 toward its previous position and adjusting the piston stroke and accordingly the engine power in the desired manner.

While the invention has been described by reference to a particular embodiment, schematically represented by the drawing, it should be apparent that numerous changes might be made in the details of the mechanism and its components without departing from the spirit and scope of the invention.

I claim:

1. Variable stroke mechanism for a reciprocating piston machine having a housing and at least one piston reciprocable in said housing, said mechanism comprising a rotor rotatably supported by said housing,

a swash plate pivotally supported on said rotor for rotation therewith and connected with said piston to correlate rotation of said rotor with reciprocation of said piston,

movable adjustment means carried on said rotor and arranged to pivotally adjust said swash plate so as to vary the stroke of said piston, and

clutch means in said housing and arranged to upon engagement, connect said adjustment means to said housing to move said adjustment means in response to rotation of said rotor and thereby pivotally adjust said swash plate.

2. The mechanism of claim 1 wherein said movable adjustment means includes a rotatable adjustment member connected with said swash plate for pivotal adjustment thereof,

first gear means connected with said adjustment member and second gear means connected with said adjustment member and said clutch means comprises first friction means having a surface engageable with said first gear means to move said adjustment member in one direction upon rotation of said rotor in a predetermined direction, and

second friction means having a surface engageable with said second gear means to move said adjustment member in the other direction upon rotation of said rotor in said predetermined direction.

3. The combination of claim 2 and further including first and second clutch actuating means carried by said housing and connected with said first and second friction means, respectively, so as to engage one of said friction means with its respective gear means upon application of a suitable fluid pressure to the associated one of said actuating means.

References Cited UNITED STATES PATENTS 225,651 3/1880 Silver 103-462 511,044 12/1883 Cooper et al. 1,241,624 10/1917 Guy 746O 1,407,047 2/ 1922 T rowbridge. 1,763,397 6/ 1930 Hutchinson. 2,465,638 3/ 1949 Eckert 74-60 3,139,006 6/1964 Budzich 91199 3,319,874 5/ 1967 Welsh et a1.

WENDELL E. BURNS, Primary Examiner US. Cl. X.R.

9l--l99; 103l62; 123-48, 58, 78; 230178 

